Forward port rest of NEWS changes as of 3.7.0

Author: ned-deily

Misc/NEWS.d/3.6.6rc1.rst

@@ -175,7 +175,7 @@ handshake to hang or fail.
 
 ..
 
-.. bpo: 31467
+.. bpo: 31647
 .. date: 2018-05-28-18-40-26
 .. nonce: s4Fad3
 .. section: Library

Misc/NEWS.d/3.7.0b1.rst

@@ -142,6 +142,7 @@ Remove the STORE_ANNOTATION bytecode.
 .. section: Core and Builtins
 
 Expose posix_spawn as a low level API in the os module.
+(removed before 3.7.0rc1)
 
 ..
 
@@ -747,6 +748,8 @@ subinterpreter C-API and a new cross-interpreter data sharing mechanism. The
 module is primarily intended for more thorough testing of the existing
 subinterpreter support.
 
+Note that the _xxsubinterpreters module has been removed in 3.7.0rc1.
+
 ..
 
 .. bpo: 32602